Table 3

Binding of the wild-type Fyn SH2 domain and two loop mutants to different peptides containing a hydrophobic residue at the P+3 or P+4 position. Peptides were labeled and Kd values were determined as described in Table 2. —, not determined.

Peptide sequenceKd ± SE (μM)Relative affinity (a/b)
Fyn WT (a)ΔBGΔBG/T216M (b)
P+3 hydrophilic, P+4 hydrophobic
Q-D-T-pY-E-T-H-L-E-T-NH24.83 ± 0.535.25 ± 0.341.72 ± 0.082.8
Y-Q-H-pY-D-L-D-L-K-D-NH27.83 ± 0.5811.12 ± 0.552.87 ± 0.142.7
H-Q-L-pY-D-D-S-F-P-M-NH210.03 ± 0.669.25 ± 0.634.61 ± 0.232.2
R-N-D-pY-D-D-T-I-P-I-NH27.60 ± 0.748.49 ± 0.490.9
P+3 hydrophobic, P+4 hydrophilic
P-Q-P-pY-E-F-F-S-E-NH20.88 ± 0.072.74 ± 0.140.3
A-P-D-pY-E-N-L-Q-E-L-NH20.66 ± 0.065.16 ± 0.190.1
A-P-E-pY-E-N-I-R-H-Y-NH20.39 ± 0.035.01 ± 0.180.1
T-Y-K-pY-D-L-F-S-D-NH24.54 ± 0.283.97 ± 0.151.1